1. Field of the Invention
The present invention relates to a rotary evaporator, and relates more particularly to a rotary evaporator of which rotary joint can be easily moved for adjusting its position along the axial direction thereof.
2. Description of the related Art
In general, a rotary evaporator has such an outline structure that a sample container which is rotated integrally with a rotary joint, with one part of which being soaked within a water bath, is connected to one end of the rotary joint that is insertedly supported by a motor rotor of a motor through a sleeve, and that a condenser mounted on a motor main body of the motor is disposed in the other side of the rotary joint.
The motor main body is structured by a stator and a motor housing. A rotation force is given to the rotor of the motor when a current is supplied to the motor. Accordingly, when the motor rotor is rotated, a rotation force is given to the sample container soaked within the water bath, through the rotary joint.
To be more specific, the rotary joint is insertedly supported by the sleeve in a insertion area. The sleeve is fixed in engagement with the motor rotor. Furthermore, the sleeve is rotatably supported by the motor main body at both ends thereof by means of bearings.
The rotary joint has a step section formed part of which is thick at the end portion of the insertion area near the sample container and the rotary joint is supported by the sleeve with an engagement between the step section and the sleeve. The step section defines an area of movement of the rotary joint along the axial direction by cooperating with a stopper ring provided in the sleeve. A sealing member is provided at the other end of the insertion area of the rotary joint near the condenser to seal between the rotary joint and the condenser by rotatably contacting with the outer peripheral surface of the rotary joint. The seal surface of the sealing member is in rotational contact with the outer peripheral surface of the rotary joint.
In the rotary evaporator described above, since the movement of the rotary joint in the axial direction is restricted by the stopper ring, the rotary joint is rotated in the state that the outer peripheral surface of the rotary joint is always contacted with the sealing member at the same position. Therefore, during a long period of used of the rotary joint, the outer peripheral surface of the rotary joint is abraded by the sealing member since the rotary joint is made of glass. Then a leakage occurs from the abraded portion of the rotary joint.
Further, when the sample container is too small to be sufficiently soaked within the water bath, it is necessary to prepare an attachment such as a joint means between the sample container and the rotary joint to have a long arm for connecting the sample container and the rotary joint so that the sample container can be sufficiently soaked within the water bath.
Furthermore, since the rotary joint is made of glass as explained above and this has a unique shape at the step section, the above described rotary joint and sleeve are not desirable from the viewpoint of cost and manufacturing steps thereof are complex and difficult.